When inspecting the interior of a stainless steel outdoor electrical box distribution box, pay attention to the copper or tin-plated terminals on the base plate or side walls. These locations are usually marked with grounding symbols for easy cable crimping. This helps to reduce the potential difference that exists between conductive parts and the earth. Equipment Protection: Grounding protects substation. Power from factory ground must be installed by a qualified electrician. Each DISTRIBUTION BOX and controller must be grounded. 26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. Grounding of the units: Attach a ground wire from one of. How to check if an area is grounded? Use a multimeter, receptacle tester, and visual inspection of bonding/earthing, ground rod, and service panel; verify ground resistance and continuity per NEC safety guidelines. You can use any multimeter, depending on what you have. It is convenient to use, and.